Relevant section of the abstract:

> Adjusting for potential confounders, use of antidepressants during the second and/or third trimester was associated with the risk of ASD (31 exposed infants; adjusted hazard ratio, 1.87; 95% CI, 1.15-3.04). Use of selective serotonin reuptake inhibitors during the second and/or third trimester was significantly associated with an increased risk of ASD (22 exposed infants; adjusted hazard ratio, 2.17; 95% CI, 1.20-3.93). The risk was persistent even after taking into account maternal history of depression (29 exposed infants; adjusted hazard ratio, 1.75; 95% CI, 1.03-2.97).

It should be noted that relative figures are the standard method of reporting effects in epidemiology, for good reasons and bad. But among them is that the regression models needed for absolute differences under more sophisticated study designs, controlling for confounding variables, etc. may not be available.

http://journals.lww.com/epidem/Fulltext/2010/01000/On_the_Or...

I was wondering the same. The original chance wasn't mentioned, only that it increases by 87%.